Hi, videohelp members!
I'm new to this forum, I tried to find solution for my problem here and at doom9, but, anyway, sorry if this topic was discussed.

I'm now working on near-lossless conversion of my school's video archive (several years, near 5Tb video data, everything in AVI DV). I managed to use the following pipeline:

1. DV 25i to MP4 50p (AviSynth with TempGaussMC is encoded with x264, --crf 15)
2. Sound from dv is converted to WAV and encoded with neroAacEnc (-q 1) to an .aac file
3. .mp4 from 1 and .aac from 2 are merged with ffmpeg to a resulting mp4

The goal is to decrease the amount of video in bytes but to save quality.
Everything is nearly fine, the quality is not decreased (actually, I don't see it). In some sense, it is increased because of good deinterlacing.

BUT, I have an audio sync issue. The audio is behind video for some 0.05475 seconds (found it out with AudioGraph for AviSynth) constant for different files or through one file (in the beginning or in the end of video).

I have read something on the issue and understood that aac encoding is not possible without this delay. Then, as I understood (please, correct me), two ways are possible: muxing with the information about this delay or just shifting of audio.
I tried -async 1 in step 3, but it doesn't work for me.

So, what it better, to shift audio manually or to deal with it using some delay flag? Or, maybe, there is some other best way to fix it? Please, advice me)
And, globally, would you improve something in this conversion workflow?